Sports events such as car- or motor racing, athletics and ice-skating, typically require accurate and fast time registration for tracking the participants during the event. Such a timing system is usually based one a transmitter-detector based scheme, wherein each participant in the event is provided with a transmitter. The transmitter may be configured to transmit packets at a certain frequency and to insert a unique identifier into the packet such that a detector is able to associate a packet with a certain transmitter.
Each time a transmitter passes or crosses an antenna of the detector, the detector may receive multiple data packets associated with the transmitter. The signal strength associated with a received data packet is a function of distance of the transmitter relative to the antenna and the particular configuration of the transmitter- and detector antennae. Hence, by assigning time-stamp information and by evaluating the signal strength associated with each data packet, the detector may determine at what time the transponder passes the detector antenna.
An example of such conventional timing system is described in U.S. Pat. No. 5,091,895. Determining the passing of a transmitter by evaluating the signal strength however has some disadvantages. In such timing system only a limited number of data packets and an equally limited number of signal strength data are available for determining the passing time. Therefore, data processing algorithms may be used in order to determine the passing time. Selection of the data used in the data processing algorithms however may influence the outcome and possibly negatively influence the accuracy of the result.
Moreover, the use of data processing algorithms may impose serious constraints in terms of processing time. In a conventional system, a complete data set of a passing transponder is needed before a data processing algorithm is able to process them thereby introducing a time delay before the detector is able to produce a passing time. This poses problems in real-time applications as the passing time is determined long after e.g. a vehicle or a skater has passed the finish line.
The problems associated with conventional systems, in particular accuracy and processing time problems associated with conventional systems, are of particular importance when the timing system is used in conjunction with video or television system. In such situations it is desirable to have a system, which is capable of accurately and quickly determining multiple passings of transponders.
Hence, there is a need in the prior art for improved timing methods and systems. In particular, there is a need in the art for the detection of a moving transmitter passing or crossing a detector antenna with increased accuracy thereby allowing fast and efficient data processing so that such timing systems are suitable for real-time applications. Moreover, there is a need in the art for detection of a detector passing or crossing a transmitter antenna allowing the detector to generate an accurate trigger signal upon passing the antenna.